Gold Nanoparticles Illuminate Defects in 3D Printed Objects

Defects in 3D printed parts can cause all sorts of problems, but they’re often so small that they can’t be easily detected, if at all. Vanderbilt University researchers are the latest to tackle the issue of detecting defects in 3D printed objects, and have come up with a new way to make those defects visible – using gold. The team embedded gold nanoparticles inside 3D printing material; once an object is 3D printed, the gold nanoparticles show up as a deep maroon color, highlighting any defects.

“3D printed materials are becoming increasingly common in our day-to-day life, from consumer goods and products to even demonstrations of 3D-printed automobiles and homes,” said Kane Jennings, Chair and Professor of Chemical and Biomolecular Engineering. “But there can be problems in the processing of 3D printed materials. Small defects or missing print layers can occur. These defects can compromise and weaken the structural integrity of the 3D printed products, causing failure.”

The research has been published in a paper entitled “Nondestructive Evaluation and Detection of Defects in 3D Printed Materials Using the Optical Properties of Gold Nanoparticles,” which you can access here. The scientists mixed the gold nanoparticles with a dissolved plastic polymer, then when the polymer hardened, it was extruded into filaments.

“It’s similar to the gold in your ring, but it has very unique optical properties that don’t degrade over time,” said civil engineering graduate student and lead author Cole Brubaker. “This is one of the first applications using gold for defect detection. We are able to inspect and detect defects that aren’t visible to the naked eye, using the optical properties of embedded gold nanoparticles. That’s a very critical step – being able to say ‘We have a defect. It’s right here.'”

After a part is 3D printed with the gold-mixed material, it is placed into a UV-Vis spectrophotometer to look for defects.

“We’re using the absorbance properties of the embedded gold nanoparticles,” Brubaker said. “You just scan light across the surface of the sample and see where the absorbance decreases inside, signaling a defect in that material. A defect can be found with one single nondestructive measurement. It’s very quick. It takes just a matter of seconds. We don’t have to rely on large sensing systems that have sensors placed all over the part.”

Authors of the paper include Brubaker, Jennings, Michael A. Davies, James R. McBride, Sandra J. Rosenthal, and Douglas E. Adams. The research was funded by the US Office of Naval Research, and patents are pending on the technology.

“There are tremendous possibilities for what we can do with this technology,” Jennings said. “We have demonstrated the 3D printed parts can be self-reporting. They self-report defects. We’re looking now at the possibility to do even more with these smart materials.”

Being able to easily locate defects in 3D printed parts will save money, time, and materials, and ensure that final parts are performing at their very best, with no unpleasant surprises cropping up after the part is put into use. According to the researchers, the gold nanoparticle technology can be used for numerous other applications, as well.

“What really gets me excited is the broad range of applications we can use this technology for,” said Brubaker. “We’ve just scratched the surface.”

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